Glomus tumors are rare, benign, and painful hamartomas, most commonly found in the subungual region. They originate from the myoarterial apparatus composed of an afferent arteriole and vascular channels lined by endothelial cells.[1] A 32-year-old gentleman presented with a painful swelling on the index finger of the left hand present for the preceding 6 years [Figure 1]. The lesion was extremely painful to touch (Love's sign positive), and the quality of life of the patient was significantly impaired. There was aggravation of pain on exposure to cold or even water at room temperature. Dermoscopy of the lesion using Dermlite DL4W dermoscope showed an ill-defined lesion under nail plate with a structure-less bluish area and linear irregular vessels [Figure 2]. Ultrasonography showed 2 cm × 3 cm hypervascular mass in the nail bed.

The mass was excised and sent for histopathological examination. Intraoperaitive dermoscopy could not be done. Histology showed collection of monomorphous neoplastic glomus cells surrounding vascular spaces lined by endothelium. The cells had round-to-oval nuclei and eosinophilic cytoplasm [Figure 3]. A diagnosis of glomus tumor was confirmed.

Because glomus tumor is a diagnosis which is difficult to arrive at solely on the basis of clinical features, dermoscopy can help. Previously reported dermoscopic findings include discrete linear vascular structure on nail plate and numerous ramified telangiectasias on nail bed and matrix,[2] altered pigmentary network, and pinkish glow.[3] However, these findings are not universal. In a recent report, instead of the pinkish hue, a homogeneous white discoloration of the nail plate was observed.[4] Thus, dermoscopy can be helpful in screening glomus tumor, however, the role of histopathological examination in the diagnosis cannot be overemphasized.

The dermoscopic differentials include hemangioma, angiokeratoma, and subungual hemorrhage. The dermoscopic hallmark of hemangioma is the presence of numerous, round-to-oval areas with a reddish or red-bluish coloration. These red lacunas (red lagoons) are pathognomonic for hemangiomas. Angiokeratoma can also have these red lacunae, alongside white to yellow keratotic structures and a whitish veil. Subungual hemorrhage is characterized by the presence of jet-black pigmentation apart from the red lacuna.

Treatment of choice is direct surgical excision. Incomplete removal of the tumor leads to recurrences. To overcome this problem, polarized light dermoscopy may be done to outline the margins of the tumor.[2]

Recurrences may also be avoided by the use of sclerotherapy and lasers (CO2, pulsed dye, etc.).[5]

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